Determination of the Range of Magnetic Interactions from the Relations between Magnon Eigenvalues at High-Symmetry κ Points

Abstract Magnetic exchange interactions (MEIs) define networks of coupled magnetic moments and lead to a surprisingly rich variety of their magnetic properties. Typically MEIs can be estimated by fitting experimental results. But how many MEIs need to be included in the fitting process for a material is not clear a priori, which limits the quality of results obtained by these conventional methods. In this paper, based on linear spin-wave theory but without performing matrix diagonalization, we show that for a general quadratic spin Hamiltonian, there is a simple relation between the Fourier transform of MEIs and the sum of square of magnon energies (SSME). We further show that according to the real-space distance range within which MEIs are considered relevant, one can obtain the corresponding relationships between SSME in momentum space. We also develop a theoretical tool for tabulating the rule about SSME. By directly utilizing these characteristics and the experimental magnon energies at only a few high-symmetry k points in the Brillouin zone, one can obtain strong constraints about the range of exchange path beyond which MEIs can be safely neglected. Our methodology is also general applicable for other Hamiltonian with quadratic Fermi or Boson operators.

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Exploiting host–guest chemistry to manipulate magnetic interactions in metallosupramolecular M4L6 tetrahedral cages

Chemical Science ◽

10.1039/d1sc00647a ◽

2021 ◽

Vol 12 (14) ◽

pp. 5134-5142 ◽

Cited By ~ 1

Author(s):

Aaron J. Scott ◽

Julia Vallejo ◽

Arup Sarkar ◽

Lucy Smythe ◽

E. Regincós Martí ◽

...

Keyword(s):

Exchange Interactions ◽

Magnetic Interactions ◽

Magnetic Exchange ◽

Guest Chemistry

The tetrahedral [NiII4L6]8+ cage can reversibly bind paramagnetic MX41/2− guests, inducing magnetic exchange interactions between host and guest.

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Structural and Magnetic Properties of Mn-Based Diluted Magnetic Semiconductors and Alloys

Research Letters in Physics ◽

10.1155/2009/406095 ◽

2009 ◽

Vol 2009 ◽

pp. 1-4 ◽

Cited By ~ 1

Author(s):

A. Alsaad

Keyword(s):

Rock Salt ◽

Diluted Magnetic Semiconductors ◽

Magnetic Semiconductors ◽

Exchange Interactions ◽

Magnetic Interactions ◽

Local Spin Density Approximation ◽

Energy Minimum ◽

Rock Salt Structure ◽

Magnetic Exchange ◽

Salt Structure

Direct supercell approach calculations of the magnetic exchange interactions in Mn-doped ScN was carried out in the local spin density approximation by using the muffin-tin-orbital Green's function method. We found that magnetic interactions are long range interactions and affected by the randomness, band gap corrections, and carrier concentrations. Using total energy minimization approach we found that the global energy minimum of MnN is obtained for zinc-blende structure. If the compound is compressed by 6%, the energy minimum corresponds to the rock-salt structure in disagreement with the experimentally observed tetragonal distorted rock-salt structure, known as -phase. An isostructural phase transition for alloys from MnN -phase to -ScN phase was found to occur at a hydrostatic pressure of 18 GPa. We predict above room temperature for Mn concentrations of about 10% in ScN : Mn system.

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The roles of chirality and polarity in novel multiferroics: MnSb2O6and Cu3Nb2O8

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314096132 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C386-C386

Author(s):

Roger Johnson ◽

Laurent Chapon ◽

Kun Cao ◽

Pascal Manuel ◽

Alessandro Bombardi ◽

...

Keyword(s):

Crystal Structure ◽

Crystal Lattice ◽

Magnetic Structure ◽

Magnetic Moments ◽

Polarization Vector ◽

Exchange Interactions ◽

Axial Rotation ◽

Magnetic Polarity ◽

Magnetic Exchange ◽

Lattice Order

At room temperature Cu3Nb2O8 has a centrosymmetric, triclinic crystal structure. If cooled below 24 K, the copper magnetic moments order with a complex, generalized helicoidal magnetic structure that breaks inversion symmetry, giving rise to ferroelectricity. Unusually, the direction of the induced electric polarization vector with respect to the helicoidal spin rotation cannot be reconciled by conventional theories of magneto-electric coupling. Instead, we show that the observed multiferroic properties of Cu3Nb2O8 may be explained through a phenomenological analysis based upon coupling between the magnetic chirality, electric polarity, and a structural axial rotation. Trigonal MnSb2O6 crystallizes with a chiral crystal structure. Typically, magnetic materials with a chiral crystal lattice order with a chiral magnetic structure, where the magnetic exchange interactions and anisotropies follow the symmetry of the lattice. The magnetism of MnSi is a classic example of this scenario, in which exotic skyrmion phases emerge out of a helical magnetic state. To the contrary, we show that the low temperature magnetic structure of MnSb2O6 is cycloidal, described by a magnetic polarity as opposed to a chirality. We demonstrate through ab-initio calculations that this magnetic structure is in fact the ground state of the symmetric-exchange Heisenberg spin Hamiltonian, which has higher symmetry than the underlying crystal lattice. Furthermore, the phenomenology may be understood by considering the coupling between structural chirality, magnetic polarity, and a magnetic axial rotation. As a result, we predict MnSb2O6 to be multiferroic with a weak ferroelectric polarization.

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Exploiting Host-Guest Chemistry to Manipulate Magnetic Interactions in Metallosupramolecular M4L6 Tetrahedral Cages

10.26434/chemrxiv.13720849.v1 ◽

2021 ◽

Author(s):

Aaron Scott ◽

Julia Vallejo ◽

Arup Sarkar ◽

Lucy Smythe ◽

Emma Regincós Martí ◽

...

Keyword(s):

Single Crystal ◽

Self Assembly ◽

Close Agreement ◽

Exchange Interactions ◽

Magnetic Interactions ◽

Magnetic Exchange ◽

Guest Molecules ◽

Space Groups ◽

Comparable Magnitude ◽

Spin Densities

Reaction of Ni(OTf)2 with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [NiII4L6]8+. By selectively exchanging the bound triflate from [OTfÌNiII4L6](OTf)7 (1), we have been able to prepare a series of host-guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [MIIX4ÌNiII4L6](OTf)6, where MIIX42− = MnCl42− (2), CoCl42− (5), CoBr42− (6), NiCl42− (7), CuBr42− (8) or [MIIIX4ÌNiII4L6](OTf)7, where MIIIX4− = FeCl4− (3), FeBr4− (4). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host-guest complexes 1-8 all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN6} vertex within a single Ni4L6 unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [NiII4] complex, and between the host and the MX4n- guest, are of comparable magnitude and antiferromagnetic in nature. Theoretically derived values for the magnetic exchange are in close agreement with experiment, revealing that large spin densities on the electronegative X-atoms of particular {MX4}n− guest molecules leads to stronger host-guest magnetic exchange interactions.

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Exploiting Host-Guest Chemistry to Manipulate Magnetic Interactions in Metallosupramolecular M4L6 Tetrahedral Cages

10.26434/chemrxiv.13720849 ◽

2021 ◽

Author(s):

Aaron Scott ◽

Julia Vallejo ◽

Arup Sarkar ◽

Lucy Smythe ◽

Emma Regincós Martí ◽

...

Keyword(s):

Single Crystal ◽

Self Assembly ◽

Close Agreement ◽

Exchange Interactions ◽

Magnetic Interactions ◽

Magnetic Exchange ◽

Guest Molecules ◽

Space Groups ◽

Comparable Magnitude ◽

Spin Densities

Reaction of Ni(OTf)2 with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [NiII4L6]8+. By selectively exchanging the bound triflate from [OTfÌNiII4L6](OTf)7 (1), we have been able to prepare a series of host-guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [MIIX4ÌNiII4L6](OTf)6, where MIIX42− = MnCl42− (2), CoCl42− (5), CoBr42− (6), NiCl42− (7), CuBr42− (8) or [MIIIX4ÌNiII4L6](OTf)7, where MIIIX4− = FeCl4− (3), FeBr4− (4). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host-guest complexes 1-8 all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN6} vertex within a single Ni4L6 unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [NiII4] complex, and between the host and the MX4n- guest, are of comparable magnitude and antiferromagnetic in nature. Theoretically derived values for the magnetic exchange are in close agreement with experiment, revealing that large spin densities on the electronegative X-atoms of particular {MX4}n− guest molecules leads to stronger host-guest magnetic exchange interactions.

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Magnetic Exchange Interactions and Supertransferred Hyperfine Fields at 119Sn Probe Atoms in CaCu3Mn4O12 Manganite

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.190.695 ◽

2012 ◽

Vol 190 ◽

pp. 695-698

Author(s):

V.S. Rusakov ◽

I.A. Presniakov ◽

A.V. Sobolev ◽

Gérard Demazeau ◽

A.M. Gapochka ◽

...

Keyword(s):

Exchange Interaction ◽

Field Model ◽

Magnetic Measurements ◽

Exchange Interactions ◽

Local Environment ◽

Electronic Configuration ◽

Magnetic Interactions ◽

Exchange Integral ◽

Hyperfine Fields ◽

Magnetic Exchange

The hyperfine magnetic interactions of 119Sn probe atoms in the CaCu3Mn3.96Sn0.04O12 double manganite by Mössbauer spectroscopy using magnetic measurements have been investigated. A consistent description of the results obtained in terms of the Weiss molecular field model by taking into account the peculiarities of the local environment of tin atoms has allowed the indirect Cu2+OMn4+ (JCuMn 51 ± 1 K) and Mn4+OMn4+ (JMnMn 0.6 ± 0.6 K) exchange interaction integrals to be estimated. Based on the KanamoriGoodenoughAnderson model, we show that the magnitude and sign of the intrasublattice exchange integral JMnMn correspond to both the electronic configuration of the Mn4+ cations and the geometry of their local crystallographic environment in the compound under study.

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Investigation of the possible pathways for magnetic exchange interactions in homobinuclear chelates of naphthazarin

Canadian Journal of Chemistry ◽

10.1139/v83-261 ◽

1983 ◽

Vol 61 (7) ◽

pp. 1500-1504 ◽

Cited By ~ 11

Author(s):

Constantinos A. Tsipis ◽

Michael P. Sigalas ◽

Vasilios P. Papageorgiou ◽

Maria N. Bakola-Christianopoulou

Keyword(s):

Metal Ion ◽

Magnetic Moments ◽

Point Group ◽

Exchange Interactions ◽

Electron System ◽

Magnetic Data ◽

Magnetic Exchange ◽

Tetrahedral Configuration ◽

Metal Centers ◽

Trigonal Bipyramidal

Homobinuclear complexes of the binucleating naphthazarinato ligand of the general formula [Formula: see text] where M = Cu, Ni, and Zn, C10H4O4 = naphthazarinato ligand, and C10H8N2 = 2,2′-bipyridyl, have been prepared and studied. In these complexes the naphthazarinato ligand, acting as a bridging unit between the two metal centers, supports the propagation of magnetic exchange interactions through its extensive π-electron system. The spectroscopic and magnetic data of the compounds showed that each metal ion is surrounded by two oxygen and two nitrogen donor atoms in a nearly tetrahedral configuration (C2v point group) with the naphthazarinato ligand adopting a centrosymmetrical structure of C2h symmetry. The room-temperature magnetic data of the copper(II) and nickel(II) homobinuclear chelates (1.32 and 1.73 BM per metal ion at 8000 G, respectively), as well as the slight decrease of the magnetic moments as the magnetic field strength decreases are indicative of the operation of antiferromagnetism in these chelates. Quantum mechanical calculations of the Hückel LCAO-MO type improved by ω-technique have been used to provide a qualitative guide to the possible pathways for the superexchange processes observed in the tetrahedral copper(II) and nickel(II) chelates, as well as to explain qualitatively why there is no antiferromagnetic interactions propagated by the bridging naphthazarinato ligand in analogous homobinuclear chelates with other coordination geometries such as square planar, square-pyramidal, trigonal bipyramidal, and octahedral.

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Systematic zone-Axis orientation of NM-scale particles for microdiffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174448 ◽

1990 ◽

Vol 48 (4) ◽

pp. 262-263

Author(s):

E D Boyes ◽

L Hanna

Keyword(s):

Real Space ◽

Dark Field ◽

Zone Axis ◽

High Symmetry ◽

Lattice Imaging ◽

Cell Level ◽

Bright Field ◽

Axis Orientation ◽

Annular Dark Field ◽

Target Designation

A VG HB501 FEG STEM has been modified to provide track whilst tilt [TWIT] facilities for controllably tilting selected and initially randomly aligned nanometer-sized particles into the high symmetry zone-axis orientations required for microdiffraction, lattice imaging and chemical microanalysis at the unit cell level. New electronics display in alternate TV fields and effectively in parallel on split [+VTR] or adjacent externally synchronized screens, the micro-diffraction pattern from a selected area down to <1nm2 in size, together with the bright field and high angle annular dark field [HADF] STEM images of a much wider [˜1μm] area centered on the same spot. The new system makes it possible to tilt each selected and initially randomly aligned small particle into a zone axis orientation for microdiffraction, or away from it to minimize orientation effects in chemical microanalysis. Tracking of the inevitable specimen movement with tilt is controlled by the operator, with realtime [60Hz] update of the target designation in real space and the diffraction data in reciprocal space. The spot mode micro-DP and images of the surrounding area are displayed continuously. The regular motorized goniometer stage for the HB501STEM is a top entry design but the new control facilities are almost equivalent to having a stage which is eucentric with nanometric precision about both tilt axes.

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A new 1-1-4 pattern of magnetic exchange interactions in a cubane core tetranuclear copper (II) complex

Polyhedron ◽

10.1016/j.poly.2021.115088 ◽

2021 ◽

Vol 199 ◽

pp. 115088

Author(s):

Azadeh Mehrani ◽

Maurice G. Sorolla ◽

Tatyana Makarenko ◽

Allan J. Jacobson

Keyword(s):

Exchange Interactions ◽

Magnetic Exchange

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